Improvement in rock-drills



UNITED STATES PATENT OFFICE.

JOIIN Y. -snITIL or ALEXANDRIA; vIReINIA.

IMPaovEMENT YIN accK-DmLLs."

Specification forming part of Letters Patent N0. 47,870, dated May 23,1865.

To all whom fitmay'couceru:

Be it known that I J OIIN Y. SMITH, ot'pAlmandria, in Vthe county ot'Alexandria and fit/tate ot' Virginia, have invented certain new anduseful Improvements in Drilling-Tools for .Boring Wells, Piercing Rocks,and other Mining or Tunneling Operations; and I hereby declare thefollowing to be a full, clear,`and exact description of the same,reference being had to the accompanying drawings, in which- Figure 1 isan elevation, and Fig. 2 an inverted plan view, of a tool or instrumentconstructed in accordance with my invention.

Rock-drills as heretofore constructed and used for cutting rock orboringwells consisted, mainly, of a straight bit-Ji. e., an ordinarychisel-edge r equally beveled on both sides. The objections to suchdrills are too well known to require much comment. It may, however, bementioned that the principal objections are, rst, liability of theirbecoming wedged in crevices' from which it is'diliicult and oftenimpossible to extract the same, which frequently necessitates theabandonment of the work second,liability of their becomingloose orunscrewedfrom" their sockets, particularly under the action ct'rotation, which is always imparted to such drills; third, slow progressof the work;` fourth, necessity of reaming the hole cut by such tools.Other V drills have been made or suggested'which, while' obviating someof the objections stated, are. subject to others peculiar to themselves.

Thus the Z-drill is costly to make and liable to break at the angles,owing to the unequal temper to Vwhich such form ot' steel isnecessari-ly liable.

The object of my invention, therefore, is to make a drill which, whileit can be easily made and kept in workin g order-. e.,sharpened orground-is calculated to penetrate therock or otherf hard substance withgreater ease and rapidity than any other drill requiring no reamer,boring a truly circular hole, not 'being liable to become wedged increvices,and having a tendency to tighten its joint in the socket, sothat there is no danger of its getting detached from the auger-stock.

The drill, subject of this patent, is composed of three or more bladesmade in one piece radiating from a common center. These blades terminateat their lower ends iu bevel-faces, constituting the cutting-ed ges.Centrally the blades are recessed, the under side of the recessedportion presenting on each blade bevelfaces onboth sides. The blades arelmade in Vone piece with a shank which is preferably square, so that acommon wrench may be used to screw the tool in or out of the socket. Onthe upper part the shank is provided with acollar and screw, whereby thetool is inserted and held .in the socketV of the auger-stock.V

The principal cutting-edges of the tool are formed by beveling the faceof each blade at an anglesu'ch as will tend to impart a slight rotarymotion to the -drill upon its own axis in the direction ot itsscrew-thread, so that each blow will only tighten the connection ol' thedrill in its socket.

In the accompanying drawings the drill shown -is composed -of threeblades, al b c, which radiate from the axis of the tool. They are madein one piece with the shank d,which is of a square cross-section, themetal' at the point of connection being of proper coucavity so as todiminish the resistance to the tool from water and accumulated earthymatters in the bottom ot' the well. At g--. e., at and, toward thecenterthe blades are recessed, whereby greater ease in making andsharpening or repairing the tool is attained and greater strength toeach cutter imparted. In the bottom ofthe recess the blades are doublebevelfaced to cut up or triturate the core that is formed by theoperation of the surrounding cutters. Theacollar h, in closing againstthe.

socket, will protect the screw.

The construction of this drill may be modined without departure from'theprinciple of my invention. Thus, instead` of radiatingthe cutters fromthe center, they may be tangential to a circle inscribed within the areaof the drill, a's`shown in Fig. 3.

Having thusfully described my invention and the manner in which the sameis or may be carried into effect, I claiml.' A rock-drill composed ofthree o'r more cutting-blades when recessed in the center or at thepoint of intersection of said blades, substantially as set forth.

2. Forming the cutting-edges of' a three or more bladed rock-drillby'beveling 011e side of said blades in suoli mnnnor as to tend to Intestimony whereof lln'f'e'signed myname rotate the. drill when strikingn blow und to to this speoioilltionbeforo two subsoribingwittrghten thesorewyjoin7 substantially as set4 nessos.

fort-h. J; Y. SMITH.

3. Forlningmutngmlg upon the recessed Witnesses portion of the blades,substantially as and for EDM. F. BROWN,

' 111e purpose set forth. Jos. L. Ooo-mas.

